1. Field of the Invention
The present invention relates to a data processing device, which is adapted to function as an external memory device of a computer, for example.
2. Description of the Prior Art
In a conventional data processing device, a data recorder, particularly an ID-1 format data recorder which forms helical recording tracks successively on the magnetic tape and is capable of recording and reproducing the desired data with high density, is proposed (ANSI.times.3.175-1990 19 mm Type ID-1 Recorded Instrumentation).
.More specifically, as shown in FIG. 1, in this type of data recorder, a magnetic tape 1 is rolled up on a rotary drum which is rotating with the prescribed speed and thereby running said magnetic tape 1 with the prescribed speed, and a magnetic head mounted on the rotary drum forms successively helical recording tracks TR (TR1, TR2, TR3, TR4, TR1, TR2, . . . ) and thus, records the desired data on said recording track TR.
Furthermore, in this event, the data recorder forms recording tracks TA, CTL and TC, which extend in a longitudinal direction of upper and lower sides of the magnetic tape 1 and records a track set identification (ID) data of the recording track TR on said recording track CTL.
The track set ID data which is composed of the absolute position information starting from the head of said magnetic tape is placed between prescribed synchronizing signals and recorded per four tracks cycle in regard to the recording track TR.
Furthermore, the recording tracks TA and TC are arranged to be able to record the user control data, and thereby reproducing the recording tracks TA, CTL and TC, the data recorded on the recording track TR with high density can be searched easily.
Furthermore, in the data recorder, in the case of recording the data on the recording track TR, the data are recorded adding parity codes for error detection correction consisted of product codes, and accordingly, the desired data can be recorded and reproduced with certainty.
More specifically, as shown in FIG. 2, the data recorder after inputting the data DATA with the prescribed unit (=36,108 [BYTE]), divides the data DATA into 306 blocks and adds the error detection correction code (i.e., consisted of C2 code) of Reed-Solomon to each block respectively.
Furthermore, after dividing each block into the first and the second fields, FIELD0 and FIELD1, the error detection correction codes of Reed-Solomon (i.e., consisted of C1 code) are added to each field, FIELD0 and FIELD1, crossing the C2 codes at right angles respectively.
With this arrangement, the reproducing data in the data recorder are error corrected in reproducing, using the C1 and C2 codes, so that the bit error rate can be improved.
Moreover, in the data recorder, in case of recording the data DATA added the Cl and C2 codes on the magnetic tape, each recording track TR is interleave processed and thus, even if the dropout occurs, the data DATA can be reproduced with certainty.
More specifically, in the data recorder, whereas the data DATA to be inputted in the order as marked with arrow marks a1, a2, . . . , an-1, an, an+1, an+2, ax-1, ax, the data DATA are recorded shifting the input order as shown with arrow marks b1, b2, . . . , bn-1, bn, and thus, said data DATA will be interleave processed.
Furthermore, in the data recorder, the synchronizing signal SYNC and sync bloc)( data ID are added to each prescribed unit (hereinafter referred to a sync block) and also preamble and postamble data are added as a whole, then the data DATA are recorded.
With this arrangement, in reproducing, in the magnetic recording device, the synchronizing signal SYNC, sync block data ID, and data DATA are reproduced referring to the track sync data contained in the preamble, and the synchronizing signal SYNC and the sync block data ID, are deinterleave processed i.e. the process of interleaving is reversed.
Furthermore, even in the case if the dropout occurs, the concentration of errors upon one place beyond error correction capacity of the C1 and C2 can be effectively avoided by deinterleave processing.
Then, in the ID-1 format data recorder for recording and reproducing the desired data, an approximately 10.sup.-10 bit error rate which is acceptable for practical use as a data processing device for chiefly measuring, is guaranteed.
If this bit error rate can be improved up to 10.sup.-15, it is considered that the extremely important data can be deposited by applying it to the magnetic tape device of the computer system for use in, for example, bank use.
Accordingly, the usability of this type of data recorder would be improved and also an application field can be expanded.
In this case, concerning this type of data recorder, if the plural files would be recorded on one magnetic tape with high density recording, it is considered that the magnetic tape can be more easily controlled.
In this event, it is considered convenient, provided the only desired file can be erased easily.
As such an erasing method, it is considered that, e.g., an erasing head would be loaded on a rotary drum. of the data recorder. However, if an erasing head is loaded on the rotary drum, the construction over the rotary drum would become complicated accordingly.